This is a really good question and the simple answer is teamwork. Almost all of us now work in small teams made up of surgeons doing the same types of operations. Centres have been most successful in increasing their optimal and complete cytoreduction rates when these teams have worked together to achieve a common goal.
Usually this has involved taking a conscious decision to try and improve rates rather than just continuing as normal, getting all the surgeons to sign up to this idea, and then educating all the other members of the team, including the anaesthetists, nurses, intensive care staff etc on what and how is going to be involved.
My experience has been that when other members of the team are involved in this way and can understand the rationale for attempting to get complete cytoreduction then the whole team starts to work towards this goal and cytoreductive rates start to increase.
There is no single surgical technique that makes a difference, rather it is a team ethos and increasing experience which leads to improved outcomes.